a) What is fertilisation? Distinguish between external fertilisation and internal fertilisation. What is the site of fertilisation in human beings.
b) How does growing embryo get nutrition from the mother's blood?

Explanation

Fertilisation is defined as the fusion of a male gamete (sperm) with a female gamete (an -ovum or egg) to form a żygote during sexual reproduction external fertilisation.
* The fusion of male gamete (sperm) and female gamate (ovum) occur outside the body. Both individuals discharge their gamates outside the body. * Development occurs outsie the body.
Ex: Frog.
Internal fertilisation :
* The fusion of gametes occurs inside the body.
* Only the male discharge sperm into female gentital tract.
* Development occurs inside the body. Ex: Humans, cattle etc.
The site of fertilisation in human beings is in the fallopian tube of female reproductive system.
The embryo gets nutrition from the mother.s blood with the help of a special tissue called placenta. This is a disc which is embedded in the uterine wall and transfer glucose and oxygen from the mother to the embryo.